1. Field of the Invention
One embodiment of the present invention relates to an image processing apparatus, bar code processing apparatus, and image processing method for processing an image such as a fluorescent bar code and the like printed on the postal matter and the like.
2. Description of the Related Art
A fluorescent bar code to be printed on the postal matter and the like has a property of becoming largely less luminous depending on the background color of a letter, and hence when part of the bars overlap the background color, the bar code cannot be correctly recognized in some cases. In this problem, if a background image such as a pattern or the like described on the letter can be correctly estimated, the expectations of being able to obtain a correct recognition result of the bar code is enhanced. However, it is difficult to estimate the background image by the processing of a conventional fluorescent bar code scanner alone in view of the property of an image obtained from the scanner.
As one of the solutions for the above problem, Jpn. Pat. Appln. KOKAI Publication No. 2004-246795 (Pat. Document 1) discloses a robust recognition method for a bar code image influenced by the background state.
In the technique disclosed in above Pat. Document 1, the apparatus is constituted of a single scanner apparatus, and hence a sufficient effect cannot be also obtained. More specifically, although the proposed technique is a technique peculiar in the threshold determination method in the binarization processing used in the bar code recognition, bar information buried in the background is not included in the representative value used in the threshold calculation process. In other words, a sufficient margin is afforded at the time of determination of the binarization processing threshold by using the part of the bars that have already been detected. Thus, the bar code that shines only at feeble intensity exceeding the margin for a reason or the like that the background color is strong is not detected at the time of binarization processing. Further, the background pattern is not detected, and hence there is no criterion for judging whether or not a part light in color is due to the influence of the background pattern. Further, there is the possibility of the confidence factor of the bar being lowered at the time of the binarization.